562 



THE AMERICAN MUSEUM JOURNAL 



as those who have just effected a land- 

 ing iipon a new continent, whose sup- 

 ply camps are estahlished, whose ax- 

 men are out, and who are heginning the 

 march. This is a field of investigation 

 where discoveries are so new that men 

 have not yet grasped the importance of 

 them and set the facts to work in ways 

 to suit the need. This is a problem of 

 the future, and as such, appeals the 

 more strongly to our imagination. 

 How is it that we have come thus far 

 upon our journey ? 



The fact of hereditary resemblance 

 must have been recognized since man 

 first gave attention to the breeding of 

 domesticated animals, or first saw that 

 his own offspring was like himself. But 

 heredity remained rather the plaything 

 of the philosopher than the problem of 

 the scientist, until the manner of indi- 

 vidual generation had become estab- 

 lished and the germ cells recognized as 

 its physical basis. All the earlier work 

 upon reproduction and development, 

 all the investigations which centered 

 around the discussion of spontaneous 

 generation, all the studies which led to 

 the cell theory were necessary to estab- 

 lish our present position, and to give 

 the investigation of heredity its point 

 of departure. With these things behind 

 it, heredity has become a subject of 

 prime interest in present-day biology, 

 and only in the last quarter century has 

 our attack begun. Two men stand out 

 as pioneers of the recent advance — 

 Mendel, whose work was the earlier 

 done but the later known ; and Galton, 

 who should Ije credited with collecting 

 valuable data and with arousing public 

 interest by his eugenic propaganda, al- 

 though his supposed "law" appears of 

 small importance when compared Avith 

 the law enunciated by Mendel. 



Without attempting an explanation 

 of either the Galtonian or the Men- 

 delian theory of heredity, a word may 

 be said in illustration of an essential 

 difference between the two. We are all 

 familiar with the tables ■|ml)lishod l)y 



insurance eom})anies. which tell us the 

 expectation of life for a man at a given 

 age. I am, say, thirty years of age. 

 The table says I may expect to live un- 

 til I am sixty-four. This is well so far 

 as it goes. It is comforting to feel I 

 have that much lease on life, even 

 though life is half spent. And this 

 knowledge does very well for life in- 

 surance companies, since it can be ap- 

 plied to thousands of policyholders 

 with a degree of certainty which places 

 the whole superstructure of the insur- 

 ance business upon a stable foundation. 

 In my particular case, however, this 

 kind of certainty is not satisfying, since 

 it can tell me nothing of my own or 

 any other individual's duration of life. 

 Though I die tomorrow or live to be a 

 hundred, my life merely counts as one 

 item in the statistics upon which such 

 tables are based. These insurance 

 tables allow us to make prophecies for 

 populations, not for individuals, and 

 this is essentially the nature of Gal- 

 ton's law of heredity. It attempts to 

 say what will be the inheritance on the 

 average, but leaves us in the dark as to 

 what will happen in the individual case. 

 If, on the other hand, after looking me 

 over, the life insurance company were 

 able to say that, barring death by acci- 

 dent, I would become an octogenarian, 

 or to say that inability to resist disease 

 would cut me off at forty, then we 

 should have the kind of prophecy it is 

 possible to make in cases of Mendelian 

 inheritance. For here we can, by 

 proper testing of the individual, fore- 

 tell the characters he will transmit to 

 his descendants. Galton's law is then 

 of value as a statistical statement, but 

 Mendel's is a guide to a fundamental 

 analysis of heredity. 



The discovery of the Mendelian 

 phenomena was not the result of any 

 feverish search for utilitarian values. 

 Mendel's interests were along theoreti- 

 cal lines, and the account of his experi- 

 ments remained buried in an obscure 

 ])ul)lication until after the same phe- 



